M.J.
Keep her safe. While it seems great to let her roam the van, it's not safe for her or your family should you be in an accident or just have to brake hard. Use a crate or special dog seatbelt during travel and be sure to make lots of stops.
Be sure to bring familiar things for her to chew once you're there. Familiar blankets or bedding can also help her relax at your destination.